Regulation of Glycoalkaloid Accumulation in Potato Tuber Discs

Bergenstråhle, Annika; Tillberg, Elisabeth; Jonsson, Lisbeth

doi:10.1016/s0176-1617(11)81078-3

Cited by 26 publications

(19 citation statements)

References 25 publications

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“…It was also found (Moehs et al, 1997;Rockhold et al, 2000) that mRNA encoding UDPGlc:solanidine GlcTase was strongly induced in wounded potato tubers. These results seem to confirm earlier suggestions (Bergenstrahle et al, 1992b) that the reaction catalyzed by UDP-glucose:solanidine GlcTase, i.e. the synthesis of c-chaconine, is a rate limiting step in the biosynthesis of a-chaconine -one of two main glycoalkaloids synthesized in potato.…”

Section: Are Glycosyltransferases Involved In the Regulation Of Tritesupporting

confidence: 92%

“…Injury-induced synthesis and accumulation of a-solanine and a-chaconine in potato tubers is a well-known phenomenon McDonald, 1997, 1999). Bergenstrahle et al (1992b) reported that the level of glycoalkaloids (a-chaconine and a-solanine) in sliced potato tubers started to increase after 24 h of incubation. This was due to de novo synthesis of glycoalkaloids since the accumulation of these glycosides was inhibited by a sterol synthesis inhibitor -tridemorph.…”

Section: Are Glycosyltransferases Involved In the Regulation Of Tritementioning

confidence: 99%

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The Formation of Sugar Chains in Triterpenoid Saponins and Glycoalkaloids

et al. 2005

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Triterpenoid saponins and structurally related steroidal glycoalkaloids are a large and diverse family of plant glycosides. The importance of these compounds for chemical protection of plants against microbial pathogens and/or herbivores is now well-documented. Moreover, these compounds have a variety of commercial applications, e.g. as drugs or raw materials for pharmaceutical industry. Until recently there were only sparse data on the biosynthesis of saponins and glycoalkaloids, especially at the enzyme level. Substantial progress has recently been made, however, in our understanding of biosynthetic routes leading to the formation of the diverse array of aglycone skeletons found in these compounds as well as mechanisms of synthesis of their sugar moieties. This review highlights some of the advances made over past two decades in our understanding of the formation and modification of sugar moieties in triterpenoid saponins and glycoalkaloids.

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Section: Are Glycosyltransferases Involved In the Regulation Of Tritesupporting

confidence: 92%

Section: Are Glycosyltransferases Involved In the Regulation Of Tritementioning

confidence: 99%

The Formation of Sugar Chains in Triterpenoid Saponins and Glycoalkaloids

et al. 2005

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“…As SGAs are not destroyed during cooking (Maga 1994;Smith et al 1996), an upper limit of 20 mg per 100 g fresh weight in potato tubers has been established for the release of commercial cultivars . However, factors associated with growth, harvest and postharvest treatments, such as drought (Bejarano et al 2000), high temperature (Morris and Petermann 1985;Lafta and Lorenzen 2000), light exposure of tubers (Dale et al 1993;Percival et al 1994;Grunenfelder et al 2006) and wounding (Bergenstråhle et al 1992;Choi et al 1994), may elevate tuber SGA content. Moreover, organically grown potatoes have been reported to contain elevated levels of glycoalkaloids (Hajslova et al 2005;Wszelaki et al 2005;Abreu et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Potato Steroidal Glycoalkaloids: Biosynthesis and Genetic Manipulation

2008

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The potato steroidal glycoalkaloids (SGAs) are important components of plant resistance against pests and pathogens but can be toxic to humans at high levels. SGAs derive their toxicity from anticholinesterase activity affecting the central nervous system and the disruptive effects on cell membrane integrity affecting the digestive system and other organs. Accordingly, current safety regulations limit their content in the edible tuber to 20 mg per 100 g fresh weight. SGA composition and level are genetically determined, with unfavourable growth conditions and inappropriate postharvest management inducing the accumulation of SGAs at levels in the tubers of "safe" cultivars beyond the maximum level set by the industry. Hence, genetic alteration of potato to prevent toxic levels of SGAs in tubers is highly desirable. At the same time, maintaining high SGA levels in other plant organs will contribute to plant resistance against pathogen and pest attacks. To this end, SGA biosynthesis and degradation should be manipulated precisely to exploit tissue-specific expression rather than whole-plant suppression of SGA production, to produce potato cultivars with SGA content enriched in the foliage but diminished in the edible tubers. Only a few details are known about the SGA biosynthetic pathway, its genes and intermediates. Research on factors that regulate SGA biosynthesis and catabolism as well as searches for genetic markers linked to total and specific SGA levels have only recently been pursued. The present review summarizes current data on these issues to encourage further discussion on SGA manipulation for safer food products.

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“…As SGA are not destroyed during cooking or frying (Smith et al 1996), commercial cultivars have been bred to contain low levels; their content in tubers should not exceed 20 mg/100 g fresh weight (Valkonen et al 1996). However, several factors associated with growth, harvest and postharvest treatments, such as drought (Bejarano et al 2000), high temperature (Lafta and Lorenzen 2000), light exposure of tubers (Dale et al 1993;Percival et al 1994) and wounding (Bergenstråhle et al 1992;Choi et al 1994), can increase tuber SGA content.…”

Section: Introductionmentioning

confidence: 99%

Potato steroidal glycoalkaloid levels and the expression of key isoprenoid metabolic genes

Krits

Fogelman

Ginzberg

2007

Planta

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The potato steroidal glycoalkaloids (SGA) are toxic secondary metabolites, and their total content in tubers should not exceed 20 mg/100 g fresh weight. The two major SGA in cultivated potato (Solanum tuberosum) are alpha-chaconine and alpha-solanine. SGA biosynthetic genes and the genetic factors that control their expression have not yet been determined. In the present study, potato genotypes exhibiting different levels of SGA content showed an association between high SGA levels in their leaves and tubers and high expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase 1 (hmg1) and squalene synthase 1 (pss1), genes of the mevalonic/isoprenoid pathway. Transcripts of other key enzymes of branches of the isoprenoid pathway, vetispiradiene/sesquiterpene synthase (pvs1) and sterol C24-methyltransferase type1 (smt1), were undetectable or exhibited stable expression regardless of SGA content, respectively, suggesting facilitated precursor flow to the SGA biosynthetic branch. The transcript ratio of solanidine glucosyltransferase (sgt2) to solanidine galactosyltransferase (sgt1) was correlated to the documented chaconine-to-solanine ratio in the tested genotypes. Significantly higher expression of hmg1, pss1, smt1, sgt1 and sgt2 was monitored in the tuber phelloderm than in the parenchyma of the tuber's flesh, targeting the former as the main SGA-producing tissue in the tuber, in agreement with the known high SGA content in the layers directly under the tuber skin.

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Regulation of Glycoalkaloid Accumulation in Potato Tuber Discs

Cited by 26 publications

References 25 publications

The Formation of Sugar Chains in Triterpenoid Saponins and Glycoalkaloids

The Formation of Sugar Chains in Triterpenoid Saponins and Glycoalkaloids

Potato Steroidal Glycoalkaloids: Biosynthesis and Genetic Manipulation

Potato steroidal glycoalkaloid levels and the expression of key isoprenoid metabolic genes

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